Abstract: Based on the fundamentals of solid mechanics,a study is conducted in this paper on the mechanism of measurement of stress sensitivity curve of rocks.Due to the plastic deformation of core sleeves,the up-load curve and the down-load cure differ a lot,which exaggerates the stress sensitivity of rocks.Actually,in measurement,cores yield only elastic deformation and not plastic deformation.In up-load process,core sleeve yields plastic deformation,and in down-process,both core sleeve and core do not yield plastic deformation.The stress sensitivity of rock in down-load process includes part of elastic deformation of core sleeve.Without the deformation of core sleeve,the stress sensitivity of core is weak and negligible.

Key words: reservoir, permeability, stress sensitivity, up-load, down-load, core analysis